Rules? What rules?
If you subscribe to a certain code, you agree to play by those rules; that seems a fair agreement.
So what you write, "you will not do anything against our rules while you are under our jurisdiction", should be answered by "yes".
Here however he's clearly not under their jurisdiction, he WAS not defaming the school or anything else that breaks that pact. So he WASN'T breaking any rules --- except possibly one of those unwritten (or so broad that they're effectively made-up retrospectively).
For example, we weren't allowed to smoke on the way home and/or when identifiable as pupils of the school; elsewhere and out of uniform you're obviously not under their jurisdiction (your parents' instead) so you cannot be told what to do.
That said, it's not clear to me why he's in that school --- of from any other place governed by a bunch that didn't foresee how this would play and disrupt their school as well as turn the school into a regional & international joke.
They are however probably preparing children very well for the world of 1950.